just focus on two customers at a time, and keep feeding them. you get a time bonus and extra money when they hit their limit
Viewing post in mini game
it's what worked for me. There's no penalty for missing customers, i stuck with the closest seats on the top two tables and just brought those customers food. I'd drop food off with one, grab another plate on my way to the other customer, and then repeat. When i gave them their final meal they gave a big chunk of cash and rewound the clock back a bit, which that time bonus is the big part of clearing the mini game